You both are quite right in your observations.
It's complicated. The thing is, that the majority of the increasingly potentials voters of
Podemos comes more from a deep disappointment with the two main parties than from a real trust on their proposals. The political scene in Spain (as very much in almost every European country), has been a matter of two, with the governments alternating between a centre-left (PSOE) and a centre-right (PP). For years, when one of those two was in charge of the government, the other one just had to wait until they "failed" so the people would punish them by giving the power to the second.
But what do you do when the party in the government is rotten by corruption, but the alternative is also so messed up with the same kind of affairs? What have happened these last years is that the electorate's disapointment has lead to a each time lower rate of participation in the elections and to a deep tiredness about politicians and institutions. With the economical crisis and the high rate of unemployment, people is just too angry to keep voting the same people who is accused of dirty affairs with the public money we as country need so much.
That anger, disappointment climate was one of the causes of the
Indignados protests of 15-M, that eventually was the seed of
Podemos. They offer what the others can't, a "clean" past of their members since they are so new on the map, youth to please the wish of young (and not so young) people who don't identificate themselves with the establishment anymore, new and "refreshing" ideas (even if some of them look fairly illusory)...and the promise of a punishment for all those ones that have used their public charges to their own benefit because being honest, almost everybody is under the impression that they can get off with almost everything right now.
The other (quite important) things they also proclaim, such as the end of the establishment and a deep reform of the State institutions, some of the economical meassures that do not convince to all, and a long etc, have of course a nice number of supporters, but not enough IMO to guarantee an absolute winning on the elections. They may also have realized that, because in the last months, as noted before, their speech has also been softened on some of those matters.
Apart from some anti-establishment, idealists young people, people of very leftish (or right, extremes usually agrees, they say) sign, or some of the very affected victims of the crisis, I don't think the majority of Spaniards have actually such a deep wish of change everything, not really. After all, until some years ago, we were a relatively happy nation if not with the politics, at least with the quiet democratic system we had achieved to establish after the dictatorship.
The number of monarchists had never been high, the republicans were more but still, most of people were not in any side. Until then, people were quite OK with the RF, kind of: "Yes, we're not exactly pro-monarchy, but we are now better than we have been during all the last two centuries, we choose our representatives and are a modern European country, and JC is a nice guy who wanted to establish a democracy and even stopped an attempt of coup, so why would we want to change? There is no need, we're fine like this", which was quite an objective, pragmatic way of thinking, IMO. But them the crisis came, the corruption scandals arised and the Royal Family was wrapped as well on messy affairs, the popularity of JC felt dramatically after Cristina and Iñaki's scandal and above all, with the Bostwana thing, and together with the boom of
Podemos everything went to a huger number of anti-monarchy feelings and the fall on the surveys.
After the abdication, things are improved, and it is true that Felipe's image is much better than his father's (during last years, that is) and people seem to be pleased with him as King. But the damage of these times has been indeed huge, and from those ones that before just didn't care abot the RF as long as they were exemplary and nice and represent the country well, many now think why should we keep a monarch instead of choosing someone as Head of State if they after all abuse equally of their positions and, at least in a republican system, you can choose another one for the job instead of expecting until the current king leaves it to his more popular son whenever he feels like. And after all, we can be now lucky with this nice guy that seems so sensible about his charge, but who knows what will his daughter be like and what will come later. Nah, monarchy is now OK but everything are advantages if we can choose (more or less one of the most common opinions about the matter).
So, to sum up, I don't actually think people here really want to kick out the monarchy and become a Republic right now, but if asked, I don't think most will be openly in favour of keeping it, as they probably would have been some years back. I trust the surveys that shows that most people want to be asked about that but, surprisingly enough, most people would vote in favour of the monarchy. It's impossible to now what we happen in the next years because people are really very divided, in this question and almost everything, but it is possible IMO that if they really want to change some aspects of the system that actually don't work, they would prefer to keep the monarchy that is the least harmful of all to maintain a minimum of stability. After all, monarchy is what we had all those years when we lived well and everything seemed to work. I think the Crown it's a good link to the happiest years, and so is still perceived even after the troubles.